Covering for an architectural opening

Abstract

A skew adjustment method and apparatus for adjusting the skewed condition of a movable rail of a window covering in which the movable rail is supported by lift cords wrapped around spools. A drive train disconnecting mechanism is used to disconnect a first spool from a second spool, the first spool is rotated relative to the second spool, thereby changing the length of the first lift cord relative to the second lift cord until the movable rail is in the desired position; and then the first and second spools are reconnected so the first and second spools rotate together. An end cap may be used to enable multiple disassemblies and reassemblies of the end cap to access the skew adjustment mechanism. In one embodiment, there are two movable rails, and the lift cords for both movable rails extend through the same rout holes in the covering. Disconnecting the first spool from the second spool may activate a mechanism that prevents the second spool from rotating.

What is claimed is: 
     
       1. A covering for an architectural opening, comprising:
 a movable rail having first and second ends, said movable rail being connected to an expandable covering; 
 first and second lift cords supporting said movable rail; 
 first and second rotatable spools mounted on said movable rail and operatively connected to said first and second lift cords such that winding up said lift cords on said spools and unwinding said lift cords from said spools extends and retracts the expandable covering; 
 a mounting member secured to said movable rail at said first end, and 
 an end cap mounted onto said mounting member at said first end so as to cover the mounting member, wherein said end cap has a normally concave shape, and further comprising a centrally located ramp member on one of said mounting member and said end cap and a mating centrally located hook on the other of said mounting member and said end cap, wherein, when said ramp member and hook are brought together, the hook travels along the ramp member and snaps onto the ramp member, flattening the normally concave shape of the end cap and creating a spring tension force that retains the end cap on the mounting member. 
 
     
     
       2. A covering for an architectural opening as recited in  claim 1 , wherein said mounting member is an end lock. 
     
     
       3. A covering for an architectural opening as recited in  claim 2 , wherein said rail extends in a longitudinal direction from said first end to said second end, and said end lock is secured to said rail by a screw extending in said longitudinal direction. 
     
     
       4. A covering for an architectural opening, comprising:
 a rail having first and second ends, said rail being connected to an expandable covering; 
 a mounting member secured to said movable rail at said first end, and 
 an end cap mounted onto said mounting member at said first end so as to cover the mounting member, wherein said end cap has a normally concave shape, and further comprising a ramp member on one of said mounting member and said end cap and a mating hook on the other of said mounting member and said end cap, wherein, when said ramp member and hook are brought together, the hook travels along the ramp member and snaps onto said other of said mounting member and said end cap, flattening the normally concave shape of said end cap and creating a spring tension force that retains said end cap on said mounting member. 
 
     
     
       5. A covering for an architectural opening as recited in  claim 4 , wherein said mounting member is an end lock. 
     
     
       6. A covering for an architectural opening as recited in  claim 5 , wherein said rail extends in a longitudinal direction from said first end to said second end, and said end lock is secured to said rail by a screw extending in said longitudinal direction. 
     
     
       7. A covering for an architectural opening as recited in  claim 4 , wherein said rail is a movable rail and is supported by first and second lift cords. 
     
     
       8. A covering for an architectural opening as recited in  claim 7 , further comprising first and second rotatable spools mounted on said movable rail and operatively connected to said first and second lift cords, respectively, such that winding up said lift cords on said spools and unwinding said lift cords from said spools extends and retracts said expandable covering.